Rotary pump and motor hydraulic transmission



May 26, 1953 T. MULLR ROTARY PUMP AND MOTOR HYDRAULIC:` TRANSMISSION Filed Aug. 29. 1947 4 Sheets-Sheet lV 4 a ff//f l JI 'lll/VIN" l a l 1 1 r l 1 n W May 26, 1953 v T. MULLER 2,639,586

ROTARY PUMP AND MOTOR HYDRAULIC TRANSMISSION Filed Aug. 29. 1947 4 Sheets-Sheet 2 lll/111111,

T. MLLER ROTARY PUMP AND MOTORHYDRAULIC TRANSMISSION Filed Aug. 29, 1947 `Maly 26, 1953 4 Sheets-Sheet 3 May 26, 195.3 MULLER 2,639,586

ROTARY PUMP AND MOTOR HYDRAULIC TRANSMISSION Filed Aug. 29. 1947 4 SheetsjSheet 4 MTF 60 60a 24% l 25 l 1 93\v 2 25 26 l /f f? J 3 5f J J. g M 50 50 d f /02 5 l I los faQ-3555;;- 7

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Patented May 26, 1953 ROTARY PUMP AND MOTOR HYDRAULIC TRANSMISSION Theodor Mller, Winterthur, Switzerland, as-

signor to Schweizerische Lokomotivund Maschinenfabrik, Winterthur, Switzerland Application August 29, 1947, Serial No. 771,316

In Switzerland May 15, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires May 15, 1962 Claims.

The present invention relates to hydraulic transmissions of the type comprising a pump unit including a pump cylinder block and a motor unit including a motor cylinder block, in which transmission not only the torque of the motor unit acts upon the driven or output shaft, but also the torque transmitted from the driving motor to the pump unit, since both the pump unit rotor and the pump cylinder block are connected for rotation, one with the driving shaft and the other with the driven shaft. By adjusting the piston stroke of the motor unit to Zero, it is 4possible to check the delivery of the pump unit in transmissions of this type, so that the shaft and the casing of the pump unit, and accordingly the input shaft and the output shaft of the transmission are obliged to rotate one with the other and the transmission operates as a coupling.

The invention further relates to that type of hydraulic transmissions in which the pump unit and the motor unit are each formed as a radial cylinder engine having a star-shaped cylinder block and a revolving casing surrounding the cylinder block and coupled for rotation therewith, both units being controlled by centrally disposed bored shafts provided with control ducts,

and in which the radial motor cylinder block is carried by a xed hub member of the stationary casing of the transmission.

In hydraulic transmissions having a control I device of the above type it vhas already been proposed to obtain a particularly compact construction by uniting the radial cylinder blocks of the pump unit and the motor unit to form a single structure, the top side of the pump cylinders being disposed radially outside, and the top side of the motor cylinders radially inside, while the connecting rods of the motor cylinders are pivotally connected to a rotatable casing surrounding the cylinders, However, this irregular distribution of the pump cylinders and the motor cylinders disposed in the same plane, results in irregular delivery of liquid and operation by shocks, of both the pump and the hydraulic motor; moreover, the cylinders have large dead spaces and the roller bearings of the casing of the motor unit have such large diameters that their practical execution is questionable.

It is an object of the present invention to provide a hydraulic transmission which avoids the mentioned inconveniences, without renouncing a compact, space-saving arrangement.

Other objects and advantages of this invention will appear from the following detailed description in which reference is made to the ac- 2 companying drawings showing by way of example several embodiments of the invention in simplified, diagrammatic representation.

Fig. l shows a transmission according to the invention in longitudinal section.

Fig. 2 is a section along the line II-II of Fig. l.

F"Figi 3 is a section along the line III-III of Fig. 4 shows in longitudinal section a transmission according to a second constructional example.

Fig. 5 shows a further modified transmission in longitudinal section.

Fig. 6 shows a fourth constructional example of a transmission in longitudinal section.

Figs. 7 and 8 each show a fragmentary longitudinal section of a further modication.

Fig. 9 is a View in elevation, partly drawn in section, of a further modified transmission.

Fig. 10 is a longitudinal section of a further constructional example of the transmission.

Fig. 1l is a fragmentary sectional view of a further modification.

Fig. 12 is a fragmentary sectional view of a modification of a detail.

Fig. 13 is a transverse section along the line XIII-XIII of Fig. 5.

Referring to Fig. 1, the pump unit includes a hollow driving or input shaft I journalled in a hollow hub member 3 of the stationary casing and formed with an integral ange for connection to a driving engine. Within the stationary casing the shaft I carries an eccentric rotor I on which is journalled the pump cylinder block 8. The shaft 4 forms an extension of shaft I beyond the rotor 'l and is journalled in a bore of the driven or output shaft 5 of the transmission. The pump rotor 'l and the cylinder block 3 are enclosed within a pump casing 5 to which the output shaft 5 is rigidly secured and to which the cylinder block 8 is connected by crank means I0 for limited relative movement with respect to the casing 6 but for rotation therewith. The pump casing 6 is supported by bearing means 9 on shaft members I and 4 on each side of rotor l. Shaft members I and 4 are bored to provide fiuid conduits leading to and from the pump unit.

The motor cylinder block 2 of the motor unit is journalled on hub member 3 at I6. This cylinder block and the pump casing 6 are rigidly connected and disposed side by side in close proximity to each other. The output shaft 5 connected to pump casing 6 is journalled in the stationary casing at Il. The entire pump unit and 3 the motor cylinder block 2 are enclosed in a motor casing 25 which is journalled by bearing means 25 in slidesZ carried by hub members at opposite ends 1ofthe stationary casing or lhousing` The motor casing 25 is rotated along with motor cylinder block 2 and pump casing 6 by linkage means 31, 38 and 39 which serve to connect motor casing 25 to pumpcasingzras -best shown in Fig. 3. The bearing means 2'6 with 'the slides 2l are slidably mounted in the hub members of the stationary casing as'best shown at"29 in Fig. 2, whereby the fluid capacity'ofthe'motor unit may be varied by moving themotorcasing 25 transversely to the axis Loffr'otation ofy the transmission by means of screw spindle 433 and hand wheel 34. The pump cylinder. block 8 carries pump pistons 2B within its 'radial fcylin'der bores, these pistons being pivotally connected to pump casing 6 by piston rods 2|. Similarly,'"the motor cylinder block 2 is provided with radial cylinder bores which.carryvmotorpistons 23 vpivotally fastened 'to vthe-motor casing 25 by-piston rods 24.

The hubmernber 3'is provided withmotorffluid inlet passage 43, 46.and-motor viiuid outletpasi sage M, i5 which communicate at their inner ends with the cylinderbores of motor cylinder block 2. The two passagesareseparated -by a web il (Fig. '3). 'The motor outlet passage44, at. its outer end, communicates .with the .pump inlet passageflll in shaft I andwith a make-up Yline IM leading "from a make-up pump |02.

'I5 in outputshaft. .The manifolds'48, 48a.and

49, whiclrlatter is connected tothe annular duct I2, damp. the delivery shocks of "thepump and the motor.

'The manner "of 'operation of 'transmissions of the described type is known. "lWhen the ange '553 'is driven, for example 'by an'electric motor, the make-up pump |32' driven bythe shaft I,

' nils all conduits which areftrayersedfbyliquid,

and the pump unit starts to pump. 4When now the motor unit ispadjusted to a vstroke equal to zero, lthis unit .absorbs no lliquid, and the pump 'casingt Ato whicntheoutput shaft 5 andflange 5I are vrigidly connected, runs atthe same .speed 'as'the input fiange'EU. The torque'of the shaft I is'then transmitted to the pumpcasing'and'from 'there to the output `Af1ange'5I (direct drive, "operation 'coupling). WhenV the axis Aof rotation'of Vthe vmotor 'casing 25 is positioned Veccentrically bymeans of'thehandwheel 34, the mol tor cylinders absorb 'a certain 'amount of liquid,

andthe pump casing `6 and accordingly the -flange 5I run more slowly than the input flange 5d. Since the eccentricityandtherefore also the liquid absorption capacity ofithe motor unit is lim- "ited, a certain minimum velocity of the output shaft 5I can be-obtainedat `'maximum eccentricity of the-axis-'of rotation of the casing'25, this minimum velocity being `for example equal to V4 of 'the number of Arevolutions of the input shaft. "During such operation, the'torque of the input "shaft AI, like during direct drive, is transmitted-tothe pumpl casing 6, but this casing still Areceives 'af' supplementary torque resulting from the cylinder block`12 workingfas-hydraulic motor.

When a :still rsmaller-speed "than the mentioned :minimum ispeed fof the outputxs'haft '5I is `required, a by-pass valve 52 is opened, which causes the surplus of the pump delivery from manifold 48a to directly return by passage 65 from the de- Llivery conduit ltothe suction conduit. A further increase of 'the 'torque at the flange 5I vis not obtained in this case.

By suitably adjusting the eccentricity of casing .25 lits :possible to also obtain a greater speed :thandirect drive or to obtain a reverse drive. If the axis of rotation of the casing 25 is displaced *by meansfof thehand wheel 34 out of its middle Vposition in the 'opposite direction to that required 'for 'reducing vthe speed of output shaft 5, the .tordue exerted-by the hydraulic motor on the u'ricminggnolonger acts in the same direction as the torque of the driving shaft but in the oppo- Ssiteidirection. "The output shaft 5 thereby receives atorque which is smaller than the driv- -ingrtorque at ange 5i) and rotates faster than the driving shaft. Since `the pump casing 6 with cylinder block .8, therefore, rotates at higher speed than the input shaft .I, and since the pump `outletiiiii in 4shaft 4 iis subjected to high pressure (as at slow speed) asthe torque driving the flange 5still has the samey direction as at slow or direct speed,.pressureliquid.has to be fed tothe'pump cylinders ,so that the direction of flow 'in pipe iinetlis reversed. ,Inlsuch case,the'pump unit actually operates as liquid-.motor and is supplied with the required.pressureliquid 4from the `motor uniti, .25 which, therefore, .operates aspump. Themotorun'it '2, 23,"25 Worksthenas a pump and the pump unit G,"I,"8.as a motor. If the axis of rotation of the casing25 is displaced so far out .of its .middle positionin vthe said ,direction that .the counter torque of the motor unit rexceeds the torque l,of the pump'unit'a. reverse drive is obtained.

When inversely thefiange'l is driven 'for .example by anelectric motor. running at constant speed, then vthe Itransmission operates also as couplinguponthe stroke of the motor unit being adjusted 'to zero. When 'thefmotorunit i. e.'its casing :25 'is 'adjusted somewhat eccentrically1 .the pumps cylinderblockB'can operate as pump and 'deliverspressure iiuidtothe motor unit,'the shaft I being capable of .turning more :slowly "than the 'flange 5I. .Upon a certaineccentricity of the motor casing, whichis, however, only a fraction .of the maximum eccentricitymentioned above, it is possible 'to Vcause the then driven shaft I to stop' without 'requiringtofopen 'the by-pass valve 52. A further increase ofthe e'ccentricity in the 'same direction results in reverse speed, whereby jpump unit and motor unit exchange their "functions asa pump and motor. 'When thewpressure 'of the working duid remains constant, a constant torque is obtained.. at the driven shaft I at all speeds of rotation of thedriven shaft whenthe transmission operates as mentioned above, the speed of 'rotation of this shaft being capable of variation from a negative value to zero and to that of the then driving shaft 5.

t is, however, also possible'to drivethefiange 5I with variable speed, andthe transmission in 'this case isadapted to4 produce aconstant speed ofthe ange 5ft-by appropriate adjustment of the 'motor unit.

The construction of the modied'transmission represented in Fig. 4 differs from that according to Fig. 1 in that the pump inlet passage aswell as the discharge passage are formed bybores'69 and 'IIJ in theinput shaft 4I `extending through the stationary'hub member'3 and driven by an engine shaft which willibe connectedto langeSG.

Accordinglyg Ibo'thannular` `ducts lI I, 'I 2 are provided in the stationary hub member 3. The shaft extension 4 and output shaft 5 do not contain any fluid ducts. Only one end cover 54 of the stationary casing needs to be provided with fluid ducts and with two manifolds 4.8 and 49; external conduits for the Working fluid can be omitted.

The shaft 5 is journalled by means of a ball bearing 1I in the cover 12 of the transmission casing. All the remaining parts rof this transmission agree with that shown in Figs. 1 3. The mode of operation also is substantially the same as that of the example shown in Figs. 1 3. Oil is fed to the pump cylinder-block 8 through duct 69, flows out of the pump through duct 10 in driving shaft I, arrives in the annular chamber I2 whence it flows through inlet passage 13 into the motor cylinder-block 2 and drives the motor unit. The oil then ows from block 2 through outlet passage 14 into the annular duct II, whence it is recycled through duct 60. The speed of output shaft 5 is adjusted by displacing slides 21, interconnected by the bracket 28, by means of the handwheel 34 (Fig. 2). The mode of operation is the same as that of the transmission shown in Figs. 1-3, with the exception of the disposition of the fluid passages, as just described.

According to Figs. 5 and 13 the pump casing 6, the motor cylinder block 2 and the output shaft 58 form a single rigid body journalled at opposite ends of the stationary housing in ball bearing 65 and at 66. In this case the motor cylinder spaces are extended to formgducts 60D in the driven shaft 58 and are controlled by the semi-annular ducts 6I and 62 extending each over one half of the circumference of the shaft 58 and communieating with the pressure and the suction space, respectively, of the pump. The input flange 50 is provided on the pump shaft 4 which contains suction and delivery conduits 11 and 18 for the pump. Conduit 11 is connected by annular duct l2 and pipe line EI to annular duct l6I Conduit 18 is connected by annular duct I I and pipe line k 80 to annular duct B2. The pump cylinder-block 8 co-operates with pump casing 6 and pump rotor 1 in like manner as in the arrangement shown in Fig. 1, with the exception of the oil-flow through the bores of the input shaft 4. Also the motor cylinder block 2 co-operates with the pistons 23, piston rods 24 and motor-casing 25 in the same manner as in Fig. l. The slides 21 and bearing means 26 also are displaced in like manner as in Fig. 1. In this construction the torque of the input shaft 4 is transmitted by the pump pistons to the pump casing 6 and is increased by a supplementary torque arising from the star-shaped cylinder block 2 of the motor unit in accordance with the adjusted eccentricity of the motor casing, both torques together being transmitted by the shaft 58 to the output flange 5 I. The operation accordingly corresponds in principle to that of the example of Figs. 1 to 4.

In the transmission according to Fig. 6, control of the motor cylinder block 2 is effected by means of the stationary hub member 3 carrying this cylinder block. The hub member is provided with fluid inlet passage 43,46 and with fluid outlet passage 44, 45. Further, the pump casing 6 and motor cylinder-block 2 together are fixed, intermediate the inner end 90 of hub member 3 and the adjacent bearing 9, to the driven shaft 92 by the flange 9I. The arrangement and cooperation of the motor cylinder-block 2 with the piston 23 and motor-casing 25, as well `as of the linkage means 31-4I, are identical with those in the example shown in Fig..5. The annular ducts l l and 12, connected t0 the inlet and discharge of Vcrown and gearwheel.

in Fig'. 2.

the pump cylinders, are connected by pipe lines and 8|, respectively to the inlet and outlet passages 4,3 and 44, respectively, of the hub member 3.

As may be seen from Fig. '7 the transmission similar tothat of Fig. 1 can deliver the torque by the intermediary of a gearwheel 88 instead of by the flange 5I, this wheel 88 being fixed on the extension output shaft 5 connected with the pump casing 6. The bore 95 in the shaft end 4 is connected by port to 89 to pipe line 60. The mode of operation of the hydraulic portion of the transmission is the same as in the case of Fig. 1.

A further modification of' the transmission according to Fig. 1 is shown in part in Fig. 8, in which the input flange 50, instead of being provided on the shaft end I in Fig. 1, is secured to the shaft end 4. Instead of flange 5| the gearwheel 88 is secured to the output shaft connected to the pump casing 6.

In Fig. 9 a modification of the transmission according to Fig. 1 is shown in which a gear crown 90 is provided on the motor casing 25,

and made to mesh with a gearwheel 9| secured to an intermediary shaft 92 carrying the flange 5I, the direction in which slide 21, 28 carrying the casing 25 is displaced being at right angles to the line intersecting the centres of the gear The remaining parts housed in casing 25 and in the two stationary hub members |00 and IOI are the same as those shown in section in Fig. 1, and the mechanism for displacing of casing 25 in the same as shown The hub member I 00 with manifold 48 and its connection to pipe line,60 is constructed in like manner as the identical parts in Fig. 7. The flange 50 of input shaft I is driven by an electric motor for example, as in the case of Fig. 1. The torque of shaft I is transmitted to the motor unit in like manner as in Fig. 1, i. e. the pump casing Within motor casing 25 is connected by linkage means to casing 25 and this latter is connected by gearwheels 90, 9I to the driven shaft 92. 'Ihe additional torque arising in the motor unit also vis transmitted through the said gearwheels to the shaft 92.

In a modification of the transmission illustrated in Fig. 10- the input shaft I is not bored. The fluid inlet and outlet passages |02 and i613 to and from the pump cylinders are provided in the shaft portion 4. These passages communicate by ports in shaft 5 with annular ducts I I and I2, respectively, in the stationary housing member |04. These ducts communicate through pipe lines 60 and 60a, respectively, with inlet passage 43 and outlet passage 44, respectively, connected at their inner ends with the cylinder bores of the motor cylinder block 2. Valve 52 for directly interconnecting the inlet and outlet ducts of the transmission is provided in the housing portion 04. This disposition permits the diameter of the shaft I to be made smaller than in Fig. l and accordingly to reduce the diameter of the portion of the hub member 3 on which the motor cylinder block 2 is mounted. Apart from the slightly different arrangement of the fluid passages, this modication operates in exactly the same manner as the transmission shown in Fig. 1.

When in a transmission according to Fig. l the inlet and outlet ports in hub member 3 would be situated in the central plane yof the motor cylinders instead of being axially displaced,

@the cylinder :block :2 must fnot be :integraler Arigidly connected pwith the vpump `casing 6; :it suffices 7vvhen the `Ycylinder block-ds connected for rotation with the pump casing and naturally ithe two members AmustyheV mutually centered. Such a disposition yis shown yin AEig-,ll -at3. The structure -and .operation of lthe transmission shown in this'zgurectherwise a-re identical 'with those of the transmission shovvn fin rFig. f1.

VF'igfllz shows 1a 4detail modification ingvvhich the outlet passage 94 :to the.pump-:cylindersds .formed vby :a central bore of the input shaft sportcn :.4 discharging by a;port 5.95 in loutput shaft 5 into manifold 48.

.'Ifclaim:

l. A hydraulic' transmission comprising Y'av stationary housing, axiallyalignedinput and output :shafts rotatably :mounted Iin lthe vhousing, Ya fpump unit Aincluding;an eccentric :rotor carried `by esaid input slfiaftffaxpump fcylin'der `:block journalled on said rotor for-relative `:rotation therewith, fsaid pump -oylinder ;b lo ck'=b eing provided-with radialcylinder bores, pump fpistons reciprocating in Asaid zbores, a-pump casing .fcylinder blockssaid lpistons -havinggpiston --rods Apivotally fastenedzto @said casing, .clank ,l means dnterconnecting said pump cylinder `block and said pump :ca-sing, :a Amotor unit1 includingr a :motor fcylinder k'block .mounted -for w rotation with said output; shaft,:.said motor. cylinder block-being :providedzwith radial cylnderbores, motolpistons reciprocatingin isaid :cylinder bores, bearing means surrounding-:said aligned 'input `andeout- Aput fshafts and mounted :in said stationary housing :for Asliding movement'ztransversely -to :the axis-,ofro'tation of. said'shaftsfa. motor casing .rotatably :mounted on 4said ibearing means, 4said :motor Ipiston :having piston .-rods ypivotally Vfastened `to said motor casing, saidpump unit Iand :said .motor fcylinder 4block being :arranged V.side 'by fside in close :proximity .to each other iwithinxsaidmotor casing, `the .pump casing and the'motor.cylinderLblockbeing connected toiform a .single structure rot-ating as .a Whole, zmeans 'l operative for .transversely moving V.said ibearing means .carrying the :motor` casing Lto .control the eccentricity of the motor casing relativelytothe axis: of rotationiof said inputand.outputlshafts, linkage .means operatively connecting the '.motor casingxto said structure to ,vprovideior synchro- .'nous :rotation of 1 said f structure f andfmotor casing upon lchangev of -eccentricity yof said-motor saidfpump cylinder block and said. motor cylinderblocl: being provdedavith ports forf-ad- :mitting and discharging .Working fluidnto and .from :said .radial cylinder bores, .and iworking ,fluid conduits lfor connecting the outlet from l,the pump'cylinders tothe `inletof tthe motorcylinders and the inlet of the pump cylinders l to Ithe outlet of:the1motor cylinders.

'2. .A hydraulicv `transmission -comprisinga stationary housing, axially aligned inputandloutput shafts rotatably; mounted in .the housing, .a pump Yunit including an.eccentric lrotor carriedfbysaid inputshaft, a pump cylinder block jour-nalled Aon `said rotor 'for -relative frotationutherewith, said pump cylinder block being provided `vvith radial cylinder bores, pumppistons reciprocating in said bores, apump ycasingnmounted; for joint rotation with said pump cylinder block, said pistonshaving pistonrodspivotally fastened vto saidy casing, crank meansfinterconnecting said-pump cylinder block .and said pump. casing, an` .axially Aextending hub, member,carriedbyfsaidstationary housing, y:a

:motor unitincluding amotorcylinderqblock supported. ori-said hub'member for rotation with said .output shaft, -said motor `cylinder block being provided-Withradial cylinder bores,motor pistons reciprocating in said cylinder bores, bearing meansdisposed at :opposite sides of said housing ffor sliding `movement transversely to the axis of rotationnf saidshafts, a motor casing rotatably ,mounted on said bearingmeans, said motorpis- `tons having piston ,rods pivotally fastened to said motor casing, .said 4pump unit and said motor cylinder block being arranged side by sidein close lproximity to each-other Withinsaidvmotor casing, .the pump casing and the motor cylinder block beingconnected to form a single structure rotat- Iingas a'.Wholefmeansoperative for transversely moving said bearing means carrying the motor ,casing to :control the eccentricity of the -motor :casing-relatively to the'axis/of rotation of said -inputand output shafts, linkagefmeans opera- .tively connect-ingthe motor casing-to said structure to provide for synchronous rotation of vsaid structure and Y-motor casing yupon a change of eccentricityfof said motor casing, said pump cylinder block and said vmotor-cylinderblock being provided with portsfor admitting and'discharging-Workinglfluid'toand from said radial cylinder ,-boresfandworkingfluid conduitstraversing said input sha-ft andlsaid hub member for-connecting the outlet from'thepump cylinders to the inlet of the motor cylinders and the-inlet of the pump cylinders to the outlet of themotor cylinders.

3. A hydraulic transmission comprising a stationary housing, axially -aligned input and output shafts rotatably mounted'in the housing, va pump unit including-an eccentric rotor carried by said input shaftfapump cylinderblock journalled on said rotor for relativerotation therewith, said pump cylinder block being provided with radial cylinder boresypump pistons reciprocating in said bores, i a pump` casing l mounted for l jointl rotation with said'pump cylinder block, said pistonshaving pistonrodspivotally fastened to said casing, crank means interconnecting said pump cylinder blockandysaid pump casing,l an axially extending hub member carried by said stationary housing, Yone of vsaid'shafts extending axially through said `hub 'memben a vmotor lunit .including ya motor cylinderblocl: supported on said hub `member for rotation with said output shaft, said motor cylinder block being provided with radial ,cylinder bores, motor pistons reciprocating in said cylinder .bores'bearingmeans disposed at opposite sides of saidhousing for sliding movement transversely to the axis of rotation of said shafts, a motor casing vrotatably Amounted on -said bearing means, said motor pistons having piston rods pivotally fas- .tenedvto said'motor casing, said pump unit and said motorfcylinder block being arranged side by sidein close proximity-to each other within said motor casing. the pump casing and the motor cylinder block being connected to form a single structurerotating as awhole, means operative for .transversely moving said bearing means carrying the motor -casing to control .the eccentricity of thefmotor casing relatively to the axis of rotation of said input and output shafts for variation of themotor piston stroke, said hub member carrying the .-motor cylinder block extending through one of said bea-ring means on the side of the motor cylinder block remote of the pumpunit, the output shaftextending through the other of saidv bearing means, linkage means operatively connecting the motor casing to said structure to arm/ide .for synhrcncus rotation ptsaidstructure and motor casing upon a change of eccentricity of said motor casing, said pump cylinder block and said motor cylinder block being provided with ports for admitting and discharging Working fluid to and from said radial cylinder bores, and Working fluid conduits traversing said input shaft and said hub member for connecting the outlet from the pump cylinders to the inlet of the motor cylinders and the inlet of the pump cylinders to the outlet of the motor cylinders.

4. A hydraulic transmission as claimed in claim 3, in which the input shaft extends through said hub member supporting the motor cylinder block, said fluid conduits in the input shaft and in said hub member extending to a point situated axially outside of said transversely movable bearing means carrying the motor casing and communicating with each other at a point situated outside of said bearing with respect to the motor casing.

5. A hydraulic transmission comprising a stationary housing, axially aligned input and output shafts rotatably mounted in the housing, a pump unit including an eccentric rotor carried by said inputl shaft, a pump cylinder block journalled on said rotor for relative rotation there- With, said pump cylinder block being provided with radial cylinder bores, pump pistons reciprocating in said bores, a pump casing mounted for joint rotation with said pump cylinder block, said pistons having piston rods pivotally fastened to said casing, crank means interconnecting said pump cylinder block and said pump casing, an axially extending hub member carried by said stationary housing, the input shaft extending axially through said hub member, a motor unit including a motor cylinder block supported on said hub member for rotation With said output shaft, said motor cylinder block being provided With radial cylinder bores, motor pistons reciprocating in said cylinder bores, bearing means disposed at opposite sides of said housing for sliding movement transversely to the axis of rotation of said shafts, a motor casing rotatably mounted on said bearing means, said motor pistons having piston rods pivotally fastened to said motor casing, said hub member extending inwardly from one side of the stationary housing through one of said bearing means, said pump unit and said motor cylinder block being arranged side by side in close proximity to each other within said motor casing, the pump casing and the motor cylinder block being connected to form a single structure rotating as a whole together with the output shaft, means operative for transversely moving said bearing means carrying the motor casing to control the eccentricity of the motor casing relatively to the axis of rotation of said input and output shafts, linkage means operatively connecting the motor casing to said structure to provide for synchronous rotation of said structure and motor casing upon a change of eccentricity of said motor casing, said pump cylinder block and said motor cylinder block being provided with ports for admitting and discharging working fluid to and from said radial cylinder bores, and working fluid conduits traversing said input shaft and said hub member for connecting the outlet from the pump cylinders to the inlet of the motor cylinders and the inlet of the pump cylinders to the outlet of the motor cylinders.

THEODOR MLLER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,545,678 Miller July 14, 1925 1,604,321 Schneider Oct. 26, 1926 1,695,289 Lee Dec. 18, 1928 1,697,253 Schneider Jan. 1, 1929 1,819,716 Mackenzie Aug. 18, 1931 2,099,630 Schneider Nov. 16, 1937 2,141,168 Bischof Dec. 27, 193'8 2,186,409 Ferris Jan. 9, 1940 2,186,556 Robbins Jan. 9, 1940 2,227,631 Carter Jan. 7, 1941 2,419,059 de Villiers Apr. 15, 1947 

